Chemicals, fertilizers and other powdered or granulated substances are commonly applied to agricultural crops. Applicator implements for applying such substances commonly include a vehicle, usually self propelled, with a box and some type of distributing apparatus downstream from a box outlet. A spinner mechanism has been used for many years to simply throw the substance centrifugally outwardly from a location beneath the box outlet.
More recently, applicator implements for dry substances have used distributing apparatus which incorporates a pneumatic source for forcing the substance through a plurality of delivery channels spaced along the rear of the implement or along a boom supported by the implement. For example, U.S. Pat. No. 3,606,097 shows a pneumatic distributing apparatus which moves substance through a plurality of channels and out a fan like distribution duct network, and U.S. Pat. No. 3,926,377 shows a centrifugal distributor unit for separating substance into a plurality of distribution tubes for output along arms extended from a vehicle.
More recently still, an applicator implement has appeared which uses a centrifugal distributor which receives substance from a vertical auger and moves it centrifugally outwardly with a blade. The substance falls into depressions which empty into delivery tubes wherein subsequently introduced air forces the substance to outputs spaced along a boom. Known distributing devices, however, exhibit deficiencies in operation which provide less than desirable performance characteristics. The latter described device, for example, is not sufficiently positive in its placement of substance among the various delivery tube openings and can result in uneven distribution of the substance among the output tubes.